T-square



(No Model.) 2 Sheets-Sheet 1.A

W. G. THORNTON.

1f-SQUARE.

No. 486,186. Patented Nov. 1,5, 1892.

- (No Model.)

2 Sheets- Sheet 2.'

W. G. THORNTON. '1T-SQUARE.

Patented Nov. 1.5, 1892.

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UNITED STATES PATENT OFFICE.

WINFIELD G. THORNTON, OF MINNEAPOLIS, MINNESOTA.

T-SQUARE.

SPECIFICATION forming part of Letters Patent No. 486,186, dated November15, 1892.

Application led November 13, 1891. Serial No. 411,787. (No model.)

To a/ZZ whom it may concern,.-

Be it known that I, WINEIELD G. THORN- TON, a citizen of the UnitedStates, residing at Minneapolis, in the county of Hennepin and State ofMinnesota, have invented certain new and useful Improvements in T-Squares, ot' which the following is a specification.

My invention relates to the well-known T- square used in drafting.

The object of the invention is to provide convenient means for adjustingthe inclination of the blade of the instrument and for enabling theinstrument when so adjusted to be accurately and readily moved along thedraft-board. This object is accomplished by the devices illustrated inthe accompanying drawings, in which- Figure 1 is a plan View of aportion of an instrument embodying my improvements in place on thedrafting-board; Fig. 2, a central longitudinal section of the same; Fig.3, a sectional detail of the head-plate; Fig. 4, a plan view showing amodification of the devices, and Fig. 5 a sectional view on the line w xof Fig. 4.

In said drawings, 1 designates a draftingboard, 2 the head of theinstrument, and 3 its blade. The blade is attached by screws orotherwise to the under side of a plate 4, that is connected by a pivot 5to a tongue 6, projecting from the,head. In the forward portion of theplate4 is a slot 7 in form of an arc of which the pivot 5 is the center,and through this slot projects a lug 8, formed on` or secured to theplate 2. The upper portion of this lug is threaded to receive a nut 9for clamping the plate4 to the head-plate atany 'point of adjustmentpermitted by the slot 7.

This arrangement enables the blade to be turned on its pivot 5 to anyangle within the limits of the slot and to be secured in place when soadjusted. A graduated scale 10 is provided in an arc along the edge ofthe head, and a pointer l1 at the end of the medial line of the blade 4enables the angle of adjustment of the blade to be readily determined.Through the center of the lug 9 and the headplate is a hole 12 in whichis abolt 13, having on its lower end a flat head 14, which engages theunder side of a metal strip 15, that is secured to the drafting-board 1with its outer edge parallel to but projecting beyond the edge of theboard. A nut 17 on the threaded end of the bolt enables the head `14 tobe clamped against the under side of the strip 15 to hold the instrumentin place on the board.

In Fig. 4 is shown an instrument of similar construction, having theends ofthe headplate 2 provided with rollers 18 bearing against theopposite edges of the strip 15, a groove 19 being cut in the board alongthe inner edge of the strip to admit the corresponding pair of rollers.The ends of the head-plate have slots 20, so that they may be sprung tocause the rollers to be held to` close contact with the strip toaccurately guide the instrument along the board.

An instrument of the construction described can be readily adjusted toplace its blade at desired angles to the edge of the board and can thenbe freely moved along the board or secured in fixed position, asdesired. I I

Having described my invention, what I claim isy 1. In a T-square, ablade, a head, a plate providing a curved slot and pivotally connectingthe blade and head, and a clamping device in such slot, permittingadjustment of the blade and serving to lock the plate to the head,substantially as set forth.

2. The combination, with a board having a projecting strip along itsedge, of a T-square composed of a blade, a head, a plate pivotallyconnecting them and providing a curved slot, and a clamping device insuch slot, permitting adjustment of the blade and serving to lock it tothe head and to lock the instrument to the marginal strip of the board,substantially as set forth.

3. The combination, with a board having a strip along its edge and agroove coinciding with the inner edge of the strip, of a T-square havinga slotted head adapted to engage the edges of the strip and to be movedalong the same, substantially as set forth.

WINFIELD G. THORNTON.,

Witnesses:

R. BLUME, lP. H. GUNcKEL.

